JP4056143B2 - Measuring method of dimensional accuracy of optical fiber fixing member, optical fiber array, optical waveguide module, and optical fiber fixing member - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical fiber fixing member for positioning and engaging an optical fiber end portion, an optical fiber array in which the optical fiber end portion is positioned and fixed, an optical waveguide module, and a method for measuring the dimensional accuracy of the optical fiber fixing member.
[0002]
[Prior art]
An optical fiber fixing member is used as a member for positioning and fixing an optical input / output end of an optical fiber with high accuracy. Such an optical fiber fixing member is disclosed, for example, in Japanese Patent Application Laid-Open No. 8-292332 (hereinafter referred to as a publication) as an optical fiber fixing substrate. This substrate is formed with a fixing groove for accommodating and positioning the optical fiber on the surface thereof by press molding. The cross-sectional shape of the fixing groove is V-shaped, and the bottom of the fixing groove is pointed or flat. Further, the above publication discloses an optical fiber array in which an optical fiber is accommodated in a fixing groove and pressed by a lid.
[0003]
[Problems to be solved by the invention]
After the optical fiber fixing member is manufactured by a method such as grinding or press molding, it is necessary to inspect whether or not the optical fiber engaging portion for positioning and engaging the optical fiber end portion is formed within a predetermined accuracy. . For example, when positioning and engaging a plurality of optical fibers, if the pitch accuracy of each optical fiber engaging portion is not within a predetermined range, it can be used for an optical fiber array that requires low optical connection loss. Can not. Conventionally, pitch dimension accuracy measurement methods include an optical measurement method for measuring from an image with a measurement microscope or the like, and a stylus measurement method using a shape measuring machine using a stylus.
[0004]
(1) When measuring the pitch dimension of each optical fiber engagement portion from an image with a measurement microscope or the like, for example, a method of measuring the pitch between the centers of the bottom surfaces of the optical fiber engagement portions can be used.
[0005]
However, if the bottom surface of the optical fiber engaging portion is sharp as disclosed in the above publication, it is difficult to obtain image contrast for detecting the center position of the bottom surface of the optical fiber engaging portion. Further, as disclosed in the above publication, even if the bottom surface of the optical fiber engaging portion is flat, if the bottom surface is a rough surface, the inclined surface constituting the fixing groove and the flat bottom surface are obtained from image processing. Difficult to distinguish. Therefore, the pitch may not be automatically measured by image processing with a measuring microscope or the like.
[0006]
For example, if the bottom surface is sharp, the slopes that support the optical fiber side surfaces of the optical fiber engaging part are in direct contact with each other, making it difficult to automatically focus on the boundary line between the slopes. Then, the reflectance with respect to the illumination light on the two slopes is close, and the boundary line between the slopes is not clear. Even if the boundary line can be observed with the naked eye, the boundary line is often mistaken for the detection of the boundary line by image processing.
[0007]
On the other hand, even if the bottom surface is flat, the illumination light is irregularly reflected by the bottom surface when the bottom surface is a rough surface. Therefore, both the bottom and the slope appear whitish, and the contrast at the boundary between the bottom and the slope is lowered. Further, when the boundary between the bottom surface and each slope is composed of a gentle curved surface, the contrast at the boundary between the bottom surface and each slope is small, and it becomes more difficult to determine the boundary from the image.
[0008]
As described above, there is a problem in that it is difficult to find the center position of the optical fiber engaging portion unless the image contrast between the flat bottom surface and the slope is low and the boundary line between the bottom surface and the slope is not clear.
[0009]
(2) On the other hand, in the measurement method using a stylus type shape measuring machine, the surface of the optical fiber engaging portion is grooved with the stylus having a tip radius of about 1 to 30 μm (the optical axis of the optical fiber engaged). ) At a right angle to the contour cross-sectional shape of the optical fiber engaging portion. Next, the obtained contour cross-sectional shape is analyzed with analysis software to determine the accuracy of the pitch and depth of the optical fiber engaging portion.
[0010]
However, in order to accurately measure the pitch, the perpendicularity between the groove direction of the optical fiber engaging portion (optical axis direction of the optical fiber, the extending direction of the optical fiber engaging portion) and the measuring direction (scanning direction of the stylus) must be It is necessary to adjust precisely.
[0011]
If this right-angle alignment is not accurate, the pitch is measured to be larger by ΔP = P ((1 / cos Δθ) −1) (ΔP: pitch error, Δθ: deviation angle from right angle, P: True pitch)), for example, a typical optical fiber fixing member with 8 V-grooves at a pitch of 250 μm—the cumulative pitch is 250 × 7 = 1750 μm. Therefore, even if Δθ is 1 degree, the pitch is measured as large as 0.27 μm. In a fixing member for a single mode optical fiber, since the recent pitch tolerance is ± 0.5 μm or less, an error of 0.27 μm in measurement is not an acceptable error. Conversely, in order to make the allowable error in measurement 0.1 μm or less, the squareness error must be 0.64 ° or less.
[0012]
Thus, also in the accuracy measurement by the stylus type shape measuring machine, it is necessary to accurately match the scanning direction of the stylus. Therefore, if it is difficult to detect the position of the bottom surface of the groove of the optical fiber engaging portion, a great effort is required to adjust the scanning direction of the stylus. Also, in order to realize automation of the alignment of the scanning direction, it is necessary to detect the position of the groove bottom surface of the optical fiber engaging portion with good contrast on the observation image.
[0013]
(3) The above problems also occur when an optical fiber array is assembled by engaging an optical fiber with an optical fiber engaging portion. For example, when the optical fiber is engaged with the optical fiber engaging portion, the vicinity of the optical fiber engaging portion is magnified from above with a microscope or the like so that the optical axis of the optical fiber is positioned at the center of the optical fiber engaging portion. Fine-tune the position of the optical fiber with a precision stage. At this time, in the conventional optical fiber fixing member, the center position of the optical fiber engaging portion is not clear, and particularly when engaging a multi-fiber optical fiber, a great effort is required. In order to automate the operation of engaging the optical fiber with the optical fiber engaging portion, it is necessary to recognize the center position of the optical fiber engaging portion by image processing. However, since the boundary detection capability by image processing is inferior to the naked eye, it is necessary to increase the contrast at the boundary.
[0014]
(4) After assembling the optical fiber array comprising the optical fiber fixing member, the optical fiber, and the holding block, the optical axis of the optical fiber is near the input / output end of the optical fiber and the end along the optical fiber. It may be necessary to inspect whether the center of the optical fiber engaging portion is along. At this time, if either the optical fiber fixing member or the pressing block is transparent, the vicinity of the optical fiber engaging portion where the optical fiber is engaged and fixed can be observed with a microscope. However, in the conventional optical fiber array, since the center of the reference optical fiber engaging portion is difficult to understand accurately as described above, a high-precision position accuracy inspection requires a great amount of labor.
[0015]
The present invention has been made under the above-mentioned background, and the problem is that the center position of the optical fiber engaging portion is obtained with high accuracy by a microscope or the like, and as a result, the shape measurement of a measuring microscope or a stylus type is performed. The optical fiber fixing member that enables accurate measurement of the optical fiber engaging portion with a machine and that can easily manufacture an optical fiber array, and that the optical fiber is an optical fiber fixing member near the optical fiber input / output end. An optical fiber array capable of easily inspecting whether it is located at the center of the joint, an optical waveguide module including such an optical fiber array, and an optical fiber fixing for measuring the dimensional accuracy of the optical fiber fixing member An object of the present invention is to provide a method for measuring the dimensional accuracy of a member.
[0016]
[Means for Solving the Problems]
In order to solve the above-described problems, the present inventors have determined the intensity of light reflected or transmitted by the bottom surface of the optical fiber engaging portion when light is applied to the optical fiber engaging portion of the optical fiber fixing member. The difference in the intensity of light reflected or transmitted by the inclined surface for supporting the side surface of the optical fiber must be large, and the intensity of the reflected or transmitted light near the boundary between the bottom surface and the inclined surface of the optical fiber engaging portion Found that it is necessary to change rapidly.
[0017]
  The present invention has been completed based on such knowledge, and in an optical fiber fixing member for positioning and engaging an optical fiber end, two inclined surfaces for supporting the side surface of the optical fiber end; An optical fiber engaging portion having a bottom surface located between the two slopes, the bottom surface being flatAnd the surface roughness Ra is 1.0 μm or less and smaller than the surface roughness of the inclined surface, and the inclined surface of the optical fiber engaging portion is formed so as to rise from the flat bottom surface, When light is applied to the bottom surface, there is a difference between the intensity of light reflected or transmitted by the bottom surface of the optical fiber engaging portion and the intensity of light reflected or transmitted by the inclined surface, and near the boundary between the bottom surface and the inclined surface. In the optical fiber fixing member, and in the optical fiber fixing member, the reflection film or the antireflection film is selected for the inclined surface and the bottom surface. Optical fiber fixing member characterized in that it is formed into a film,In the above-described optical fiber fixing member, a plurality of the optical fiber engaging portions are provided, and a flat bottom surface of the optical fiber engaging portions is configured to be positioned on the same plane. An optical fiber fixing member, wherein the optical fiber fixing member is obtained by molding a moldable material, and in the optical fiber fixing member, the material is a glass material, The gist of the optical fiber fixing member is any one of a polymer material and a composite material composed of a polymer material and an inorganic filler.
[0018]
  The optical fiber fixing member described above, the optical fiber engaged with the optical fiber engaging portion, and the side surface of the optical fiber engaged with the optical fiber engaging portion are pressed, and the optical fiber end portion is An optical fiber array having at least the optical fiber fixing member transparent, and the optical fiber array and an optical waveguide optically connected to the optical fiber array. An optical waveguide module having an element The
[0019]
  Further, in the above-described method for measuring the dimensional accuracy of the optical fiber fixing member, the boundary position between the inclined surface and the bottom surface using the contrast of the observation image between the inclined surface and the bottom surface of the optical fiber engaging portion of the optical fiber fixing member. And measuring the dimensional accuracy of the optical fiber engaging portion by measuring the pitch of the two or more optical fiber engaging portions based on the boundary position. In the measuring method of dimensional accuracy and the measuring method of dimensional accuracy of the above-mentioned optical fiber fixing member using a stylus type shape measuring machine, the slope and bottom surface of the optical fiber engaging portion of the optical fiber fixing member, The boundary position between the inclined surface and the bottom surface is determined using the contrast of the observed image, the extending direction of the optical fiber engaging portion is obtained based on the boundary position, and the obtained extending direction is used as a reference. The shape measurement The pitch and / or depth of the two or more optical fiber engaging portions is adjusted based on the contour cross-sectional shape of the optical fiber engaging portion obtained by adjusting the measuring direction of the machine and tracing the adjusted measuring direction with a stylus. The gist of the method is to measure the dimensional accuracy of the optical fiber fixing member, which is characterized by measuring the dimensional accuracy.
[0020]
In order to trace the optical fiber engaging portion with the stylus, the stylus of the shape measuring machine may be moved either by moving the fixing base that fixes the optical fiber fixing member. Also good.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0022]
The optical fiber fixing member of the present invention has an optical fiber engaging portion for positioning and engaging an optical fiber end portion on the surface. The optical fiber engaging portion is a flat surface that supports the side surface of the optical fiber when the end portion of the optical fiber is engaged, and is positioned between the two inclined surfaces so as not to contact the optical fiber. Includes the bottom.
[0023]
Here, a typical shape of the optical fiber engaging portion has a concave portion, and two inclined surfaces serving as opposing surfaces of the concave portion for supporting the side surface of the optical fiber end portion are formed from the top to the bottom of the concave portion. The distance between the opposing surfaces is gradually narrowed as it goes, and the bottom of the concave portion where the slope ends forms the bottom surface.
[0024]
The first aspect of the present invention is a portion where the bottom surface and the slope are connected in a cross section perpendicular to the optical axis of the optical fiber supported by the two slopes of the optical fiber engaging portion, that is, a boundary between the bottom surface and the slope. The slope of the bottom and the slope of the slope are discontinuous and are not connected by an arc.
[0025]
At this time, the slope of the optical fiber engaging part rises suddenly from the flat bottom surface, and when light is irradiated from the-direction, the reflection direction by the bottom surface does not match the reflection direction by the slope, and the reflection direction from the bottom surface along the slope is changed. When viewed with the naked eye, the reflection direction changes abruptly at the boundary between the bottom and the slope.
[0026]
When the light is irradiated from the direction perpendicular to the flat bottom surface, and the reflected light from each part of the optical fiber fixing member is viewed from the light irradiation direction, the intensity of the reflected light is reflected by regular reflection at the bottom surface of the optical fiber engaging portion. Since the incident direction of light and the reflection direction do not coincide with each other on the slope, the intensity of the reflected light is small.
[0027]
Furthermore, when observing from the direction perpendicular to the bottom surface of the optical fiber engaging portion with a microscope, the illumination light can be irradiated from the vertical direction by epi-illumination. At this time, if the focus of the microscope is adjusted to the bottom surface, From the boundary of the slope to the slope, it quickly deviates from the depth of focus of the microscope, and only the flat bottom is clearly observed. In this way, the boundary line between the bottom surface and the slope can be recognized.
[0028]
On the other hand, in the section perpendicular to the optical axis of the optical fiber supported by the two inclined surfaces of the optical fiber engaging portion, the inclination is continuously inclined from the bottom surface to the inclined surface in the portion where the bottom surface and the inclined surface are connected. In an optical fiber engaging part that is shaped to be connected to a slope by an arc even if it is a flat bottom, for example, when light is irradiated as described above, the light and darkness of the bottom and the slope occurs. The boundary is blurred and cannot be distinguished.
[0029]
  Next, in the second embodiment of the present invention, the contrast between the bottom surface and the slope when the optical fiber engaging portion is irradiated with light from above or below the flat bottom surface of the optical fiber engaging portion. Reflective film to be largerOrAn antireflection film is selectively formed on the slope and the bottom. The direction of light applied to the bottom surface may be from the vertical direction or from an oblique direction.
[0030]
As this form, a part in which a high contrast is generated by the shape of the optical fiber engaging part as in the first form described above, or a reflective film is selectively formed only on the bottom by a method such as lithography, or a part excluding the bottom In some cases, an antireflection film is selectively formed, or a reflection film and an antireflection film are used together to increase the intensity of reflected light only at the bottom surface. When a reflection film or an antireflection film is used, the slope of the bottom surface and the slope of the slope may be discontinuous at the boundary between the bottom surface and the slope.
[0031]
Furthermore, in the third embodiment of the present invention, the surface roughness of the flat bottom surface of the optical fiber engaging portion is set to 1.0 μm or less in terms of Ra. By reducing the surface roughness of the bottom surface, irregular reflection due to the bottom surface can be reduced, and the contrast between the slope and the bottom surface can be increased. Further, when the surface roughness of the bottom surface is reduced, light scattering on the surface is reduced, so that the amount of light transmitted to the bottom surface of the optical fiber fixing member increases. Therefore, when the surface on which the optical fiber fixing member is installed has a high reflectance, only the bottom surface can be brightly illuminated by the return light reflected from the installation surface. On the other hand, if a black surface having a low reflectance is used for the surface on which the optical fiber fixing member is installed, only the bottom surface is made black, and the inclined surface is light-scattered so as to appear white. Even in the third embodiment, the slope of the bottom surface and the slope of the slope may be discontinuous at the boundary between the bottom surface and the slope.
[0032]
As described above, when light transmission at the bottom surface is used, it is preferable not to directly enter the reflected light from the bottom surface into a microscope or the like in order to increase the contrast. That is, it is desirable to shift the direction of illumination from the direction of observation with a microscope or the like. When measuring dimensions directly from an image like a measuring microscope, it is necessary to observe from the direction perpendicular to the bottom surface in order to prevent distortion of the observed image. Therefore, it is desirable to arrange the illumination direction so as to be shifted from the vertical axis.
[0033]
on the other hand. When the stylus is in the way and it is difficult to observe from the vertical direction like a stylus type shape measuring machine, the bottom surface may be observed from an oblique direction. In this case, it is preferable that the observation direction is inclined by 30 to 70 degrees with respect to the bottom surface because the contrast between the slope and the bottom surface is increased.
[0034]
As described above, the surface roughness of the bottom surface of the optical fiber engaging portion is preferably as small as possible, but if the surface roughness is 1.0 μm or less in terms of Ra, a practical contrast can be obtained, and the surface roughness should be 0.5 μm or less. It was found that very good contrast can be obtained.
[0035]
Also, combining the first form and the second form, the first form and the third form, the second form and the third form, the first form, the second form and the third form. You can also. For example, according to the optical fiber fixing member that combines the first form and the second form, and according to the optical fiber fixing member that combines the first form and the third form, An optical fiber fixing member can be obtained in which the contrast of the slope is large and the boundary line can be clearly distinguished.
[0036]
Further, when the optical fiber engaging portion is observed with a microscope by setting the opening angle of the two inclined surfaces for supporting the side surface of the end portion of the optical fiber to be in the range of 50 to 100, preferably 50 to 90 degrees, the focus is lightened. When matched with the bottom surface of the fiber engaging portion, the slope near the boundary with the bottom surface is blurred out of the depth of focus, so that only the bottom surface can be observed more clearly.
[0037]
In the case of an optical fiber fixing member having a plurality of optical fiber engaging portions, the flat bottom surface of each optical fiber engaging portion is preferably located on the same plane. In such an optical fiber fixing member, when a plurality of optical fiber engaging portions are allowed to enter the field of view of the microscope, each optical fiber engaging portion can be focused on the bottom surface, and the pitch between the optical fiber engaging portion centers can be set. It is easy to measure and evaluate the interval.
[0038]
The material for the optical fiber fixing member may be any material that can be finely processed or molded, such as glass, crystallized glass, and a polymer material (for example, resin) that is transparent in a cured state. A transparent glass that can be observed from the back side and a glass having a low thermal expansion coefficient is particularly preferable. Examples of processing methods include grinding and molding. In particular, in the case of molding, the mold for transferring the optical fiber engaging portion can be of a shape that is reversed with respect to the shape of the optical fiber engaging portion to be molded. It is preferable that the molding surface of the mold for transferring the bottom surface is at least flat and further in a smooth state.
[0039]
For example, when a mold material having a smooth surface is ground with a grindstone, a molding surface that transfers the inclined surface of the optical fiber engagement portion is processed with a grindstone, and the bottom surface of the optical fiber engagement portion is between these molding surfaces. A part of the smooth surface of the mold material is left as a molding surface for transferring the material. In this way, after processing the molding surface for transferring the slope, it is not necessary to process the molding surface for transferring the bottom surface of the optical fiber engaging portion in a separate process, and the bottom surface of each optical fiber engaging portion is transferred. Since the molding surfaces are on the same plane, there is no need to match the height of the molding surfaces. Further, a sharp edge is formed between the molding surface for transferring the bottom surface and the molding surface for transferring the inclined surface, and this edge portion forms a boundary line between the bottom surface and the inclined surface of the optical fiber engaging portion.
[0040]
In the case of molding, glass having a low yield point and a small average thermal expansion coefficient between the molding temperature and room temperature is preferable. As such glass, SiO₂, B₂O_ThreeAnd some containing ZnO. Molding uses an ordinary method for producing a high-precision molded product. Further, in terms of mass productivity, etc., it does not reach mold molding, but grinding is also possible. In this case, it is preferable to make the bottom surface of the optical fiber engaging portion smooth by a smooth surface finishing grindstone.
[0041]
The optical fiber fixing member described so far is a transparent member, and the optical fiber is engaged with the optical fiber engaging portion, and the optical fiber is pressed from the upper surface by the holding block, and the optical fiber end portion is lighted. An optical fiber array can be obtained by being sandwiched between fiber fixing members. In such an optical fiber array, the optical fiber engaging portion and the optical fiber end portion engaged and fixed to the optical fiber engaging portion can be observed with a microscope from the back side of the surface on which the optical fiber engaging portion is formed. . Observing from the direction perpendicular to the bottom surface of the optical fiber engaging portion clearly distinguishes the bottom surface of the optical fiber engaging portion as described above, so that not only the end surface of the optical fiber but also the end portion of the optical fiber connected to the end surface is an optical fiber. It can be easily inspected whether the engagement portion is accurately engaged and fixed. As the pressing block, for example, a plate-like member made of a material such as glass used for an optical fiber fixing member can be used.
[0042]
The portion of the holding block that contacts the side surface of the optical fiber is desirably a flat surface so that the side surface of the optical fiber can be reliably pressed.
[0043]
In assembling the above optical fiber array, for example, the optical fiber end is engaged with the optical fiber engaging portion, an adhesive such as a photo-curing resin or a thermosetting resin is applied thereto, and the optical fiber is applied with the holding block. The side surface of the optical fiber engaged with the engaging portion is pressed so that the optical fiber is held between the holding block and the optical fiber fixing member. In this state, the adhesive is cured, and the end portion of the optical fiber is fixed to the optical fiber fixing member. The optical fiber fixing member and the presser block in the present invention are not limited to those made of a transparent material, but the end portion of the optical fiber engaged and fixed as described above is observed or the photocurable resin is cured. For this purpose, it is preferable to use a transparent material.
[0044]
In the above optical fiber array having an adhesive in part or all of the space surrounded by at least any two members of the optical fiber engaging portion, the optical fiber, and the holding block of the optical fiber array, the optical fiber engagement It is preferable that the refractive index difference between the adhesive and the optical fiber fixing member is large because the one having a higher reflectance on the bottom surface of the part can easily distinguish the bottom surface. After the optical fiber array is assembled, the optical connection side end face of the optical fiber array is polished.
[0045]
Using the optical fiber array described so far, an optical waveguide module can be obtained by optically connecting the optical fiber array and the optical waveguide element. Examples of the optical waveguide element include a branched optical waveguide element, a light receiving element, a light emitting element, and an optical waveguide element provided with other optical elements. Further, there is an optical waveguide module in which an optical fiber array is optically connected through an optical waveguide element, in which at least one of the optical fiber arrays is the optical fiber array of the present invention.
[0046]
【Example】
Examples of the present invention will be described below.
[0047]
[Example 1]
A cemented carbide base material containing tungsten carbide as a main component was precision processed to obtain a cemented carbide block with a base having a width of 5 mm, a length of 5 mm, and a height of 14 mm. Only the upper surface of the cemented carbide block was subjected to surface processing so that the surface roughness Ra was 0.04 μm. Nine V-grooves with an opening angle of 60 degrees were processed at 250 μm intervals on the upper surface of the cemented carbide block using a dicing saw and a diamond grindstone so as to be aligned in the center with a width of 5 mm. In the processing, the V groove depth was set so that an unprocessed surface (upper surface described above) having a width of about 20 μm remained between the V grooves.
[0048]
Next, planar processing is performed from the bottom surface of the V-grooves at both ends toward the outside of the V-groove to the same depth as that of the V-groove, and as shown in FIG. A V-groove mold 1 having 4 was obtained.
[0049]
By the above molding die manufacturing method, the flat portion 5 having a width of about 20 μm and a surface roughness Ra of 0.04 μm is formed at the tip of the concave-convex groove 4 of the V-groove molding die 1.
[0050]
This V-groove forming mold was combined with other mold parts to form an optical fiber fixing member forming mold as shown in FIG. That is, the above-described V-groove forming die B, the forming die D for transferring and forming the pedestal portion on which the optical fiber coating portion is placed, and the V-groove forming die B and the forming die D are integrated by the fixed frame E The cavity Z was configured using a mold, and a barrel mold F for molding the side surface of the optical fiber fixing member and a lower mold G for molding the bottom surface of the optical fiber fixing member.
[0051]
In order to give moldability to the molding surface of each mold, a carbon-based release film H was formed in advance by 500 angstroms by an ion plating method.
[0052]
Next, SiO₂13.3 wt%, B₂O_Three32.2 wt%, ZnO 44.5 wt%, Al₂O_Three5.5 wt%, Li₂It contains 4.5 wt% of O, and SnO₂Was preformed hot to obtain a glass preform J having a width of 3.8 mm, a length of 10.5 mm, and a thickness of 2.05 mm with a curved edge. The glass preform J is placed in the mold Z of the mold Z as shown in FIG. 3, and the mold is heated to 560 ° C. in an inert atmosphere, and the mold is 150 kgf / cm.²The glass preform J was press-molded for 90 seconds. Then, it cooled to room temperature, weakening the applied pressure, and took out the molded article C from the type | mold.
[0053]
As shown in FIG. 4, eight V-grooves C-2 constituting the optical fiber engaging portion C-1 are formed on the upper surface of the optical fiber fixing member C, which is a molded product, at a pitch of 250 μm. Further, a step surface C-3 that is one step lower than the V-groove forming surface C-4 is formed in order to place the optical fiber covering portion.
[0054]
As shown in FIG. 1, the bottom surface 13 of the V-groove 14 has a flat portion (flat portion) having a width of about 20 μm. When the surface roughness of the V groove 14 was measured with a surface roughness meter having a stylus tip diameter of 5 μm, the surface roughness of the V groove bottom surface 13 was 0.04 μm in Ra. In other words, the flat surface of the V-groove bottom surface 13 is a surface to which the above-mentioned concave / convex groove tip flat portion 5 shown in FIG. 2 is transferred, and is found to be molded to the same surface roughness as the concave / convex groove tip flat portion 5 of the mold 1. It was. ―How. The surface roughness of the slope 12 of the V groove 14 was 0.2 μm in Ra. Further, at the portion where the V-groove bottom surface 13 and the inclined surface 12 are connected, the inclination of the V-groove bottom surface 13 and the inclination of the inclined surface 12 in the vertical section with respect to the extending direction of the optical fiber engaging portion are discontinuous. Furthermore, the contrast between the V-groove bottom surface 13 and the inclined surface 12 in a state where light is irradiated from above or below the optical fiber engaging portion 15 was clearly discernable with the naked eye.
[0055]
The V-groove accuracy of the optical fiber fixing member was measured as follows. The magnification of the measuring microscope was set to 100 times on the screen, and an image viewed from the vertical direction with respect to the V groove bottom surface 13 of the optical fiber fixing member 11 was captured. The illumination light source uses a halogen lamp, and in order to prevent temperature rise due to illumination, heat rays are cut by a heat ray absorption filter and irradiated from the vertical direction with respect to the bottom surface of the V-groove of the optical fiber fixing member 11. To match. Next, the edges on both sides of the V-groove bottom surface (the boundary between the bottom surface and the slope) were automatically detected by image processing, and the center position of both edges was calculated to obtain the center position of the V-groove bottom surface 13. A similar operation was repeated for each V-groove 14, and the pitch accuracy of the V-groove 14 was measured by measuring the distance between the center positions of the V-groove bottom surface 13. In the optical fiber fixing member 11 of the example, the brightness of the image on the bottom surface of the V groove is different from that on the inclined surface, and the edges on both sides of the bottom surface of the V groove can be easily and accurately detected easily from the contrast. As a result, in the V-groove pitch measurement, the analysis error in the same measurement image was about 0.1 μm.
[0056]
The above is the case where glass is used as the material, but the same applies to the case where a polymer material that can be molded and is transparent in the cured state is used.
[0057]
The following (1) to (3) films were formed on the optical fiber engaging portion of the optical fiber fixing member, respectively, and the contrast on the slope and bottom surface could be further increased.
[0058]
(1) Either a reflection film or an antireflection film is formed on either the slope or the bottom.
(2) Antireflection film on the slope and reflection film on the bottom
(3) A reflection film is formed on the slope and an antireflection film is formed on the bottom.
[Example 2]
The V-groove pitch accuracy of the optical fiber fixing member of Example 1 was measured as follows using a measurement microscope. A metal mirror was placed on the observation table of the measurement microscope, and an optical fiber fixing member was placed thereon. In addition, illumination light was applied from the upper side of the V-groove to the bottom of the V-groove at 60 degrees so that the reflected light did not directly enter the optical system of the measurement microscope. Observation was performed from the direction perpendicular to the bottom surface of the V groove, and the focus was adjusted to the bottom surface of the V groove. With the above arrangement, only the bottom surface of the V groove of the optical fiber fixing member of the example was projected brightly. When the V-groove pitch was measured by the same method as in Example 1, it was possible to measure with the same measurement accuracy. In comparison with the naked eye, the V-groove bottom surface was easily discriminated compared to the setting in Example 1.
[0059]
[Example 3]
A V-groove pitch was measured in the same manner as in Example 2 except that a black surface-treated aluminum plate was placed in place of the metal mirror and the illumination light was slightly increased. With the above arrangement, only the bottom surface of the V-groove of the optical fiber fixing member of the example could be projected in black. When the V-groove pitch was measured by the same method as in Example 1, it was possible to measure with the same measurement accuracy. In comparison with the naked eye, the bottom of the V-groove was easily discriminated compared to the setting of Example 2.
[0060]
[Example 4]
The V-groove accuracy of the optical fiber fixing member of Example 1 was measured with a stylus type shape measuring machine as follows. A precision stage composed of an XY stage and a rotary stage was used as a sample mounting table, and a sample fixing jig was fixed on the rotary stage. The fixing jig used was a black upper surface similar to the aluminum plate of Example 3. The optical fiber fixing member was fixed on the fixing jig with the V-groove direction being substantially perpendicular to the scanning direction of the stylus. In order to observe the bottom surface of the V-groove, a microscope was installed parallel to the V-groove direction and inclined 45 degrees above the bottom surface of the V-groove, and light was irradiated from a direction perpendicular to the bottom surface of the V-groove.
[0061]
First, while looking at the microscope, the stylus is dropped on the bottom surface of the V-groove, and then the Y stage is driven to move the optical fiber fixing member in a direction perpendicular to the scanning direction of the stylus. At this time, if the direction of the V-groove and the scanning direction of the stylus are not exactly perpendicular, the tip of the stylus is detached from the bottom of the V-groove by driving the stage. When the tip of the stylus is detached from the bottom surface of the V-groove, the rotary stage is finely adjusted, and the direction of the optical fiber fixing member is adjusted until the stylus is not detached from the bottom surface of the V-groove. In the observation image of the optical fiber fixing member reflected in the microscope, only the flat part of the bottom surface of the V-groove is reflected in black, so that it is very easy to determine the boundary position between the slope and bottom surface of the V-groove, and therefore the direction alignment is also very high. It was easy. By adjusting the direction, the extending direction of the optical fiber engaging portion, that is, the V-groove direction can be obtained correctly, and the squareness error between the V-groove direction and the scanning direction of the stylus should be 0.64 degrees or less. And the stylus scan direction was accurately adjusted.
[0062]
The X stage is driven, the surface of the optical fiber engaging portion is traced at right angles to the groove direction with a stylus, and the profile cross-sectional shape of the optical fiber engaging portion is measured. Next, the obtained contour cross-sectional shape was analyzed with analysis software, and the accuracy of the pitch and depth of the optical fiber engaging portion was obtained. Since the perpendicularity between the V-groove direction of the optical fiber engaging portion and the scanning direction of the stylus exactly matches, the tolerance in measurement could be 0.1 μm or less.
[0063]
[Example 5]
Using the optical fiber fixing member of Example 1, as shown in FIG. 5, a single mode optical fiber F is engaged and disposed in each of the optical fiber engaging portions C-1 of the optical fiber fixing member C, and transparent. The holding fiber M made of glass was used to hold the optical fiber, and it was bonded and fixed with an ultraviolet curable resin. Next, the end face of the optical fiber fixed by the optical fiber fixing member C and the holding block M was polished together with the end face of the optical fiber fixing member and the holding block end face to produce an optical fiber array Y. With respect to this optical fiber array, the bottom surface of the optical fiber engaging portion is discriminated in the same manner as in Examples 2 and 3, and it is confirmed that the position of the single-mode optical fiber that is engaged and fixed is not displaced along the optical axis direction. It was easy to confirm. Further, as shown in FIG. 6, the optical fiber array Y and the optical waveguide element W were connected so that the optical fiber and the optical waveguide were optically connected to obtain an optical waveguide module.
[0064]
The optical fiber array and the optical waveguide module obtained in the present embodiment have not only the position of the end face of the optical fiber but also the optical axis accurately along the direction of the optical fiber engaging portion at least near the end face of the optical fiber connected to the end face. Met.
[0065]
【The invention's effect】
According to the present invention, the center of the optical fiber engaging portion is obtained with high accuracy by optical measurement or stylus measurement, and as a result, an optical fiber fixing member that can easily manufacture an optical fiber array can be obtained.
[0066]
Further, by using such an optical fiber fixing member, it is possible to easily inspect whether the optical fiber is located at the center of the optical fiber engaging portion of the optical fiber fixing member in the vicinity of the optical fiber input / output end, It is possible to obtain an optical fiber array and an optical waveguide module in which the optical axis is accurately along the direction of the optical fiber engaging portion at least in the vicinity of the end face of the optical fiber connected to the end face as well as the end face position of the optical fiber.
[0067]
Furthermore, according to the dimensional accuracy measuring method of the present invention, the dimensional accuracy of the pitch and depth of the optical fiber engaging portion of the optical fiber fixing member can be accurately measured.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an optical fiber engaging portion of an optical fiber fixing member according to an embodiment.
FIG. 2 is a perspective view of the concave-convex groove mold for forming a V-groove according to the embodiment as viewed obliquely from above.
FIGS. 3A and 3B are process diagrams for explaining a method of manufacturing an optical fiber fixing member by the optical fiber fixing member forming die according to the embodiment, wherein FIG. 3A is a front sectional view before pressing, and FIG. (C) is a front sectional view during pressing, and (d) is a sectional side view.
FIG. 4 is a perspective view of an optical fiber fixing member according to the embodiment.
5A and 5B are explanatory views showing an optical fiber array according to the embodiment, in which FIG. 5A is a perspective view, and FIG. 5B is a front view.
FIG. 6 is a perspective view of the optical waveguide module of the embodiment.
[Explanation of symbols]
11 Optical fiber fixing member
12 Slope
13 Bottom
14 V groove
15 Optical fiber engaging part
F optical fiber

Claims (9)

In the optical fiber fixing member for positioning and engaging the optical fiber end,
An optical fiber engagement portion having two slopes for supporting a side surface of the optical fiber end portion and a bottom surface located between the two slopes;
The bottom surface is formed flat and the surface roughness Ra is 1.0 μm or less and smaller than the surface roughness of the inclined surface, and the inclined surface of the optical fiber engaging portion rises from the flat bottom surface. When the bottom surface is irradiated with light, there is a difference between the intensity of light reflected or transmitted by the bottom surface of the optical fiber engaging portion and the intensity of light reflected or transmitted by the slope, and the bottom surface and the slope An optical fiber fixing member characterized in that the intensity of the reflected light or transmitted light is changed near the boundary between 2. The optical fiber fixing member according to claim 1, wherein a reflection film or an antireflection film is selectively formed on the inclined surface and the bottom surface. 3. The optical fiber fixing member according to claim 1 , wherein a plurality of the optical fiber engaging portions are provided, and a flat bottom surface of the optical fiber engaging portions is positioned on the same plane. An optical fiber fixing member. 4. The optical fiber fixing member according to claim 1 , wherein the optical fiber fixing member is obtained by molding a moldable material. The optical fiber fixing member according to claim 4 , wherein the material is any one of a glass material, a polymer material, and a composite material composed of a polymer material and an inorganic filler. 6. The optical fiber fixing member according to claim 1 , pressing an optical fiber engaged with the optical fiber engaging portion, and an optical fiber side surface engaged with the optical fiber engaging portion. An optical fiber array comprising a holding block that sandwiches the optical fiber end portion with the optical fiber fixing member, and at least the optical fiber fixing member is transparent. An optical waveguide module comprising the optical fiber array according to claim 6 and an optical waveguide element optically connected to the optical fiber array. In the measuring method of the dimensional accuracy of the optical fiber fixing member according to any one of claims 1 to 5 , the contrast of the observation image between the inclined surface and the bottom surface of the optical fiber engaging portion of the optical fiber fixing member is used. Measuring the dimensional accuracy of the optical fiber engaging portion by determining the boundary position between the slope and the bottom surface and measuring the pitch of two or more optical fiber engaging portions based on the boundary position; Measuring method of dimensional accuracy of optical fiber fixing member. Claims 1 using shape measuring stylus type in dimensional accuracy measuring method of the optical fiber fixing member according to any one of 5, the inclined surface and the bottom surface of the optical fiber engagement portion of an optical fiber fixing member The boundary position between the inclined surface and the bottom surface is determined using the contrast of the observed image, the extending direction of the optical fiber engaging portion is obtained based on the boundary position, and the obtained extending direction is used as a reference. The pitch of two or more optical fiber engaging portions based on the profile cross-sectional shape of the optical fiber engaging portion obtained by adjusting the measuring direction of the shape measuring machine and tracing the adjusted measuring direction with a stylus A method for measuring the dimensional accuracy of an optical fiber fixing member, wherein the dimensional accuracy of depth is measured.

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